Rocket fuel comprising dimethylnitros-amine and a liquid oxidizer



United States Patent of Ohio N0 Drawing. Filed Oct. 25, 1962, Ser. No. 234,279 16 Claims. (Cl. 60-35.4)

This invention relates to a novel method of rocket propulsion and the fuels used therein.

In the use of liquid rockets, it is desirable that the fuel employed be relatively stable, of high density, and be a liquid over a relatively wide temperature range. The requirement of remaining liquid is imposed because rockets must be capable of firing under all types of adverse climatic conditions. Thus, a rocket must be capable of firing in the cold of the arctic or in the heat of the desert.

The fuels employed in the rockets are subjected to the same climatic conditions as the rocket itself since the fuels must be stored in the rocket itself or in close proximity to it. Fuels now in use frequently give problems in this regard since their boiling point is too low or their freezing point is too high. Also, present rockets fuels are not sufi'iciently stable and have densities which are relatively low. Thus, they are hazardous and require a large volume storage container, thereby increasing the size of the rocket.

An object of this invention is to provide novel rocket fuels which are quite stable, relatively dense, and which have a relatively high boiling point and a relatively low freezing point. A more specific object of this invention is to provide as a rocket fuel the compound dimethyl nitrosamine either alone or in admixture with known rocket fuels such as hydrazine or dimethyl hydrazine. A still further object of this invention is to provide a novel method for imparting thrust to a rocket engine, which method employs as the fuel the compound dimethyl nitrosamine either alone or in combination with known rocket fuels.

The compound dimethyl nitrosamine has a boiling point of 150 C., a melting point of 29 C. and a density of 1.006 grams per cc. In using dimethyl nitrosamiue as a rocket fuel, I employ either relatively pure dimethyl nitrosamine alone or in admixture with hydrazine or hydrazine derivatives, preferably lower alkyl substituted hydrazine derivatives such as unsymmetrical dimethylhydrazine. Dimethyl nitrosamine is miscible with hydrazine or hydrazine derivatives. Thus, my fuels are homogeneous. The precise proportions employed can vary depending upon the fuel characteristics desired. I have found that any fuel mixture containing dimethyl nitrosamine in combination with hydrazine or a hydrazine derivative is satisfactory.

Typical fuel mixtures of dimethyl nitrosamine with hydrazine or hydrazine derivatives are illustrated by the following table in which all parts and percentages are by weight.

Table 1 Fuel Parts by Weight Dimothyl nitrosamine 5 15 5 15 llydrazinc 5 5 Unsynnnetrlcal dimethyl hydrazine 2 6 5 Mononicthyl hydrazine 26 6 In use, my fuels are burned in combination with an oxidizer. I have found that dimethyl nitrosamine is not, in itself, hypergolic. Thus, when employing dimethyl nitrosamine as the fuel, it can be mixed with the oxidizer prior to firing and ignited by a conventional igniter. In

Patented July 6, 1965 using my fuels in which dimethyl nitrosamine is admixed with hydrazine or a hydrazine derivative, the fuel itself is hypergolic. Thus, in this case, the fuel and oxidizer are injected simultaneously into the firing chamber in which they ignite spontaneously upon contact. In supplying thrust to a rocket vehicle, my fuels burn with the oxidizer to create gases which are ejected through a Venturi nozzle to provide the thrust.

Typical and conventional liquid oxidizers which can be employed in burning my fuels include liquid oxygen, fuming nitric acid, nitrogen tetroxide, hydrogen peroxide, and the like. In a preferred form of my invention, tetranitromethane is employed as the oxidizer in combination with relatively pure dimethyl nitrosamine alone as the fuel. On combustion, one mole of tetranitromethane gives off approximately three and one-half moles of oxygen. In burning, one mole of dimethyl nitrosamine requires approximately two moles of oxygen. Thus, in use, the dimethyl nitrosamine is employed in molar excess over the tetranitromethane. A preferred fuel comprises from about 65 to about Weight percent of tetranitromethane in admixture with dimethyl nitrosamine.

When my fuels, as outlined above, are burned with an oxidizer in a rocket engine, they are found to impart high thrust to the rocket and to perform satisfactory as rocket fuels. As an example, when 35 parts of dimethyl nitrosamine are burned with 65 parts of red fuming nitric acid, a specific impulse of about 268 seconds is obtained. Burning 50 parts of dimethyl nitrosamine with 50 parts of liquid oxygen gives a specific impulse of about 299 seconds; a 70-30 mixture of hydrogen peroxide with dimethyl nitrosamine gives about 280 seconds, and a 72.5- 27.5 mixture of tetranitromethane with dimethyl nitrosamine gives about 276 seconds. Still further examples are the burning of 5 parts of dimethyl nitrosamine, 69 parts of nitrogen tetroxide and 26 parts of monomethyl hydrazine to give a specific impulse of about 286 seconds; burning 15 parts of dimethyl nitrosamine, 25 parts of hydrazine and 60 parts of nitrogen tetroxide to give a specific impulse of about 287 seconds, or burning 5 parts of dimethyl nitrosamine, 22 parts of unsymmetrical dimethylhydrazine and 73 parts of nitrogen tetroxide to give a specific impulse of about 283 seconds.

My novel propellants can also contain finely divided readily oxidizible metals such as aluminum, beryllium, and the like. Such metals can be present in a concentration up to about 30 percent by weight of the total fuel.

Having fully defined my novel rocket propellants and their method of use, I desire to be limited only within the lawful scope of the appended claims.

What is claimed is:

l. A process for producing thrust in a reaction motor comprising burning in a reaction motor a fluid mixture of dimethyl nitrosamine and a liquid oxidizer.

2. The method of claim I wherein said oxidizer is liquid oxygen.

3. The method of claim 1 fuming nitric acid.

4. The method of claim 1 nitrogen tetroxide.

5. The method of claim 1 hydrogen peroxide.

6. The method of claim 1 tetranitromethane.

7. The method of claim 6 wherein said dimethyl nitrosamine is present in molar excess over said nitromethane.

8. The method of claim 1 wherein said dimethyl nitrosamine is present in admixture with a fuel selected from the group consisting of hydrazine and lower alkylsubstituted hydrazines.

9. A rocket fuel comprising a homogeneous mixture wherein said oxidizer is wherein said oxidizer is wherein said oxidizer is wherein said oxidizer is of dimethyl nitrosamine with a compound selected from 15. The fuel of claim 10 wherein said oxidizer is tetrathe group consisting of hydrazine and lower alkyl-substinitromethane. tuted hydrazines. 16. The fuel of claim 15 wherein said dimethyl nitnos- 10. A rocket fuel consisting essentially of dimethyl amine is present in molar excess over said tetranitronitrosamine in combination with a liquid oxidizer. 5 methane.

11. The fuel of claim 10 wherein said oxidizer is liquid oxygen References Cited by the Examiner 12. The fuel of claim 10 wherein said oxidizer is fuming UNITED STATES PATENTS nitric acid.

13. The fuel of claim 10 wherein said oxidizer is nitro- 10 3088272 5/63 Stengel et 60*354 gen tetroxide.

14. The fuel of claim 10 wherein said oxidizer is hydro- CARL QUARFORTH Pnmary Emmmer' gen peroxide. REUBEN EPSTEIN, Examiner. 

9. A ROCKET FUEL COMPRISING A HOMOGENOUS MIXTURE OF DIMETHYL NITROSAMINE WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF HYDRAZINE AND LOWER ALKYL-SUBSTITUTED HYDRAZINES. 